Field of the Invention
The present invention relates to the technical field of projector devices, and in particular, to a method for controlling a projector and a projector applicable to the method.
Description of the Related Art
So far, the projectors are mainly realized by three kinds of display technologies, that is, the CRT projection technology, the LCD projection technology and the DLP projection technology developed in recent years.
CRT is an English abbreviation of Cathode Ray Tube, translated as cathode ray tube. As an imaging device, it is the earliest and most widely used display technology. This projector can be decomposed into the input signal source R (red), G (green) B (blue) three CRT tube screen, and the phosphor lights under the action of high pressure, systematically magnified, convergent, showing a color image on the big screen. The optical system and CRT tube form a projection tube. The so-called three gun projector is composed of a projector comprising three projection tubes, due to the use of light source, also known as active projection. CRT technology is mature, so the images displayed are rich in color, good in reducibility with the ability for adjusting geometric distortion. However, the important technical indicators image resolution and brightness are mutually restricted, which directly affect the brightness value of a CRT projector. Up to now, the brightness value is always hovering below 300 Lm. In addition, the operation of the CRT projector is complicated. In particular, the convergence adjustment is tedious, the body is bulky, and is only suitable for installation in places where the ambient light is weak and relatively fixed, and should not be moved.
LCD is an English abbreviation of Liquid Crystal Device. LCD projector is divided into two kinds as liquid crystal board and liquid crystal light valve. Liquid crystal is a substance between liquid and solid. It does not shine, and the working nature is greatly influenced by temperature, and its working temperature is −55 C˜+77 C. The projector utilizes the photoelectric effect of the liquid crystal, that is, the arrangement of the liquid crystal molecules changes under the influence of the electric field, affecting the light transmittance or reflectivity of the liquid crystal cell, thereby affecting its optical nature, resulting in images with different gray levels and colors.
DLP is an English abbreviation of Digital Light Processor, translated as digital light processor. The birth of this new projection technology enabled us to finally realize digital information display with the ability to capture, receive and store digital information. DLP technology is an epoch-making revolution in the field of display. Just as CDs have a huge impact on audio, DLP will open a new chapter in video projection display. The key technical points of its DLP projector with DMD (Digital Micromirror Device) digital microreflector as a light valve imaging device are as follows: the first is the digital advantage. The use of digital technology has achieved the image grayscale of 256-1024 level, the color of 2563-10243 kinds, the disappearance of the image noise, the stability of the picture quality, wherein accurate digital images can be reproduced continuously, and lasting. The second is the reflection advantage. The application of the reflective DMD device makes the total optical efficiency of the imaging device more than 60%, and the uniformity of contrast and brightness is excellent. On the DMD block, the area of each pixel is 16 μm*16 μm, and the interval is 1 μm. According to the number of DMD used, the DLP projector can be divided into single chip, two chips and three chips machine. DLP projector has high definition, uniform picture, sharp color, and three chips machine can be more than 1000 lm in brightness. It abandoned the traditional sense of convergence, which can be free to zoom, and the adjustment is very convenient; however, the resolution is not high, with uncompressed resolution of 800×600 (some models of the latest product resolution has reached 1280×1024). However, due to the new technology, the difficulty and cost of maintenance are not low.
Basically all types of projectors have the same principle for displaying images. The projector first shines light onto the image display element to produce an image, which is then projected through the lens. The image display element of the projector includes a transmission type that generates an image by light transmission and a reflection type that generates an image by using the reflection light. No matter what kind of type, it is necessary to divide the light of the projection lamp into red, green and blue colors to produce various color images. Because the element itself can only be monochrome display, it is necessary to use three-color elements to generate three-color parts. And then the three-color images are combined into one image through the prism, and finally projected onto the screen through the lens.
In the case of DLP projectors, projectors need to project their images onto a white screen to maximize the projected image quality. When the screen is not white, such as the screen is yellow, red, green, or the surrounding environment is yellow, red and other interference, the projected image quality is affected by screen color or ambient light color, resulting in image distortion.
The reason for the image distortion is that the projector does not have the function of automatic white balance based on screen color or ambient light color. Projector just projected the original image as realistic as possible. There is no adaptive self-adjusting capability for different color screens or different color ambient light.